import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

public class DownloadImage {

    private final static Logger logger = LoggerFactory.getLogger(DownloadImage.class);

    public static void downLoadFromUrl(String urlStr, String fileName, String savePath) throws IOException {
        logger.info("start to download image...");

        URL url = new URL(urlStr);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        // 设置超时间为3秒
        conn.setConnectTimeout(3 * 1000);

        // 防止屏蔽程序抓取而返回403错误
        conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");

        // 得到输入流
        InputStream inputStream = conn.getInputStream();

        // 获取自己数组
        byte[] getData = readInputStream(inputStream);

        // 文件保存位置
        File saveDir = new File(savePath);
        if (!saveDir.exists()) {
            saveDir.mkdir();
        }

        File file = new File(saveDir + File.separator + fileName);
        FileOutputStream fos = new FileOutputStream(file);
        fos.write(getData);
        if (fos != null) {
            fos.close();
        }

        if (inputStream != null) {
            inputStream.close();
        }

        logger.info("download successfully.");

    }



    private static byte[] readInputStream(InputStream inputStream) throws IOException {
        final int length = 1024 * 10 * 2;
        byte[] buffer = new byte[length];
        int len = 0;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        while ((len = inputStream.read(buffer)) != -1) {
            bos.write(buffer, 0, len);
        }
        bos.close();
        return bos.toByteArray();
    }
}
